Cover lift tab release

ABSTRACT

To avoid bending of the free end portion of the sheet metal finger tab as it is swung upwardly to tear the skirt at upright score lines and release the cover as disclosed in U.S. Pat. No. 3,422,984, such end portion is formed with a center curl and separate curls inclined upwardly and outwardly from the ends of the center curl and along the side edges of the free end portion of the tab.

O United States Patent 1 m1 3,731,832 Foster I May 8, 1973 [54] COVER LIFT TAB RELEASE FOREIGN PATENTS OR APPLICATIONS [15] l nytiglloli lqhn A. Foster, Rockford, Ill. 1,040,867 9/1966 Great Britain ..2l5/46 A [73] Assignee: J. L. Clark Manufacturing (10.,

Rockford, 11L Primary ExaminerGeorge T. Hall Attorney-Wolfe, Hubbard, Leydig, Voit & Osann [22] Filed: July 9, 1971 [21] Appl. No.: 161,236 [57] ABSTRACT To avoid bending of the free end portion of the sheet [52] U.S. Cl. ..2l5/46 A metal finger tab as it is swung upwardly to tear the [51] Int. Cl. ..B65d 43/02 kin at u ri ht score lines and release the cover as dis- [58] Field Of Search ..2l5/46, 46 A, 42; closed in s Pat. 3 422 9 4 h end portion is 220/54 27 formed with a center curl and separate curls inclined upwardly and outwardly from the ends of the center [56] References Cited curl and along the side edges of the free end portion UNITED STATES PATENTS of the 3,371,812 3/1968 Foster ..2l5/46 A 1 Claim, 12 Drawing Figures 3,422,984 1/1969 Foster ..220/59 Patented May 8, 1973 2 Sheets-$heet l INVENTOR. /'///V A /"4//2P mow:

COVER LIFT TAB RELEASE BACKGROUND OF THE INVENTION U.S. Pat. No. 3,422,984 discloses a sheet metal cover having a depending skirt crimped around and sealed against the lip bead of a container and formed with circumferentially spaced score or tear lines at opposite sides and at the upper end of a depending tab which is curved circumferentially and is. of sufficient arcuate width to resist bending intermediate its ends whereby to induce upward tearing of the skirt at said score lines as the tab is swung outwardly and upwardly to an upright position. After such tearing, the released cover may be lifted easily off from the lip bead of the container.

SUMMARY OF THE INVENTION The present invention improves upon the patented construction by reinforcing the free end portion of .the lift tab so as to increase the resistance of such portion to bending during the lifting to tear the skirt and release the cover. This objective is achieved by forming the metal of the free end portion of the lift tab into a plurality of separate curls which are arranged "in end to end relation and angularly disposed at a substantial angle relative to each other so as to reinforce the tab against bending in the area above the free end and in the course of lifting the end portion outwardly and upwardly. The reinforcement of the tab is increased by forming upwardly inclined curls along both side edges of the tab end.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a jar equipped with a cover having a lift tab embodying. the present invention.

FIGS. 2 and 3 are sections along the lines 2-2 and 3- 3 of FIG. 1.

FIG. 4 is a view like FIG. 1 with the tab lifted and the score lines torn.

FIG. 5 is a perspective view of the cover blank before the tab is curled.

FIG. 6 is an elevational view of the cover looking toward the tab.

FIG. 7 is a perspective view of the cover after removal from the jar.

FIG. 8 is a plan view of the cover blank.

FIGS. 9 and 10 are fragmentary sections taken along the lines 9-9 and l0-10 of FIG. 6. FIGS. 11 and 12 are views similar to FIG. 6 showing modified forms of the tab.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, the improved lift tab indicated generally at 13 is incorporated in a sheet'metal cover 11 having a depending skirt 12 including the upper part of the tab 13 telescoped down over and hooked around and beneath a downwardly facing shoulder 14 around the lower edge of a bead 15 preferably spaced somewhat below the lip 16 ofa container 17..The cover thus held compresses a gasket 18 against the lip to provide the desired tight seal. For withstanding the high pressures frequently required, the container is preferably composed of rigid material such as glass and the cover is formed of an aluminum alloy about 0.0105 of an inch thick.

In a conventional drawing operation, the outer part of the blank is drawn downwardly to form the cylindrical skirt 12, the tab portion 21 being curved as shown in FIG. 5 and constituting a depending extension of the skirt and having the same curvature as the skirt. In the course of the drawing, the metal of the skirt is scored and weakened along upright lines 22 and 23 across the skirt.

In accordance with the present invention, the tab 13, in its final form (FIGS. 1 and 6) is formed by curling the metal of laterally separated parts of the free end portion of the tab 21. In each instance, the metal is curled outwardly, then upwardly, and finally inwardly toward and against the outer surface of the tab to form curls, at least one of which is disposed at the side of the tab and extends upwardly and outwardly at a substantial angle to tab end, thus increasing the rigidity and reinforcing the end portion of the tab so as to provide increased resistance to bending in the course of lifting the tab outwardly and upwardly to force tearing of the metal along the score lines 22, 23. In the preferred embodiment, three of such separate curls indicated at 24, 25 and 26 are employed, these being arranged end to end around the free end of the tab with the central curl 24 disposed substantially parallel to the plane of the cover and the side curls extending outwardly and up wardly at an angle greater than 30 and preferably as near to 45 as possible. Each of the curls is substantially straight and cylindrical in uniform cross-section throughout its length, the diameter of each being about 0.065 of an inch.

The cover with the skirt 12, the tab 13, and the curls 24, 25 and 26 arranged as above described, is formed from a stamped out circular blank 28 shaped as shown in FIG. 8 with a projection 29 for forming the curls having substantially parallel side edges 30, 31 and laterally spaced notches 32, 33 which divide the end of the projection into a central tab 39 from which the curl 24 is formed, and side tabs 35 and 36 from which the curls 25 and 26 are formed. The latter tabs are disposed at a shorter radius than the central tab and the ends 37, 38 thereof diverge away from the notches at approximately the angles at which the curls 25, 26 are disposed in the final cover construction.

After the drawing operation to convert the blank into the skirted and scored form shown in FIG. 5, all three of the curls 24, 25 and 26 may be formed in a single axial movement of inner and outer dies, one supporting the cover (FIG. 5) and the other surrounding die having properly shaped and positioned] surfaces for engaging the tab ends 37, 38 and 39 substantially simultaneously. In the remaining closing of the male and female dies, the metal of all of the tabs is rolled outwardly, upwardly and finally inwardly to form all three of the curls 24, 25 and 26 of the cross-section and in angular positions above described, this being possible in high production operation with dies of proper shape actuated in proper timed relation.

After filling the container 17, the cover 11 is placed thereon with the skirt 12 including the upper portion of the tab telescoped down over the container lip 15 which, when composed of glass, is molded to the shape shown in FIGS. 2 and 3. Then, in a conventional crimping operation, the lower edge portion of the skirt and the connected upper portion of the tab are bent inwardly and hooked around in beneath the shoulder 14 thus compressing the gasket 16 against the lip end to form the desired tight seal capable of withstanding relatively high internal pressures.

As disclosed in the aforesaid patent, one side edge 40, the left one in this instance, is disposed substantially vertically and substantially in line with the score line 22. The other side edge 41 of the tab 13 is inclined upwardly and laterally beyond the upper end of the curl 26 to the score line 23 so that the latter is angularly spaced a substantial distance from the main part of the tab 13. With this arrangement and in releasing the cover by outward swinging and lifting of the tab 13 to the position shown in phantom in FIG. 3, the skirt 12 is first torn along the score line 22 and then, as the lifting of the tab is continued, the skirt is torn along the right hand score line 23. With the skirt torn along both score lines as indicated at 40' and 41' as shown in FIGS. 4 and 7, the cover is released from the bead and may be lifted off from the jar by continuing the swinging and lifting of the tab to the phantom position shown in FIG. 3.

While the useof the three curls 24, 25 and 26 constructedand arranged as above described is preferred in order to provide the desired increased reinforcement of the free end portion of the tab, adequate strengthening may be achieved by the modified curl arrangements shown in FIGS. 11 and 12. In FIG. 11, a substantially greater number of curls 43 are formed in the same manner as in the preferred construction around the edge of the free end portions of the tab 13. The several curls thus employed impart a generally arcuate curvature to the free end edge of the tab as shown in FIG. 1 1.

Alternatively, the central curl 24 may be omitted and two curls 44, 45 be employed (FIG. 12) and disposed at the same substantial angles relative to the plane of the cover as curls 25, 26 of the preferred construction. The curls thus are arranged in the form of a V with the inner ends of the two disposed adjacent each other at the apex of the V.

It will be apparent that with the tab 13 formed with one or more curls at a side edge of the tab at the free end thereof and inclined upwardly at the substantial angle shown, the free end portion of the tab is made rigid and strengthened to effectually resist bending of the tab as it is swung outwardly and upwardly to force tearing of the skirt and release of the cover from the container bead. By forming the curls from laterally spaced parts of the tab end having ends 36, 37 inclined at the desired eventual inclination of the curls, the latter are arranged in close end to end relation to achieve the desired reinforcement of the free end portion of the tab 13.

I claim:

I. A circular sheet metal container cover having a depending skirt, an arcuate tab constituting a depending extension of said skirt, said tab having one substantially vertical side edge and having an opposite inclined side edge which diverges away from said vertical side edge upon progressing upwardly, a first upright score line formed in said skirt on one side of said tab and disposed in substantial alinement with said vertical side edge, a second uprightscore line formed in said skirt on the opposite side 0 said tab and spaced angularly from said inclined side edge by a substantial distance, a first curl extending across the free end of said tab substantially parallel to the plane of the cover, second and third curls extending upwardly from opposite ends of said first curl and diverging away from one another at a substantial angle upon progressing upwardly, said second curl extending to said vertical side edge whereby an obtuse included angle is defined between said second curl and said vertical side edge, said third curl being positioned generally in line with said inclined side edge and forming a continuation of said side edge, and all of said curls curving outwardly and then upwardly and finally inwardly so as to impart rigidity to the free end portion of the tab and thereby increase the resistance of the tab to transverse bending during outward swinging and lifting thereof to force tearing of said skirt along said score lines. 

1. A circular sheet metal container cover having a depending skirt, an arcuate tab constituting a depending extension of said skirt, said tab having one substantially vertical side edge and having an opposite inclined side edge which diverges away from said vertical side edge upon progressing upwardly, a first upright score line formed in said skirt on one side of said tab and disposed in substantial alinement with said vertical side edge, a second upright score line formed in said skirt on the opposite side of said tab and spaced angularly from said inclined side edge by a substantial distance, a first curl extending across the free end of said tab substantially parallel to the plane of the cover, second and third curls extending upwardly from opposite ends of said first curl and diverging away from one another at a substantial angle upon progressing upwardly, said second curl extending to said vertical side edge whereby an obtuse included angle is defined between said second curl and said vertical side edge, said third curl being positioned generally in line with said inclined side edge and forming a continuation of said side edge, and all of said curls curving outwardly and then upwardly and finally inwardly so as to impart rigidity to the free end portion of the tab and thereby increase the resistance of the tab to transverse bending during outward swinging and lifting thereof to force tearing of said skirt along said score lines. 